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From: Christophe Leroy <>
To: Benjamin Herrenschmidt <>,
	Paul Mackerras <>,
	Michael Ellerman <>
Subject: [PATCH] powerpc/kasan: fix early boot failure on PPC32
Date: Wed, 31 Jul 2019 06:01:42 +0000 (UTC)
Message-ID: <> (raw)

Due to commit 4a6d8cf90017 ("powerpc/mm: don't use pte_alloc_kernel()
until slab is available on PPC32"), pte_alloc_kernel() cannot be used
during early KASAN init.

Fix it by using memblock_alloc() instead.

Reported-by: Erhard F. <>
Fixes: 2edb16efc899 ("powerpc/32: Add KASAN support")
Signed-off-by: Christophe Leroy <>
 arch/powerpc/mm/kasan/kasan_init_32.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/mm/kasan/kasan_init_32.c b/arch/powerpc/mm/kasan/kasan_init_32.c
index 0d62be3cba47..74f4555a62ba 100644
--- a/arch/powerpc/mm/kasan/kasan_init_32.c
+++ b/arch/powerpc/mm/kasan/kasan_init_32.c
@@ -21,7 +21,7 @@ static void kasan_populate_pte(pte_t *ptep, pgprot_t prot)
 		__set_pte_at(&init_mm, va, ptep, pfn_pte(PHYS_PFN(pa), prot), 0);
-static int kasan_init_shadow_page_tables(unsigned long k_start, unsigned long k_end)
+static int __ref kasan_init_shadow_page_tables(unsigned long k_start, unsigned long k_end)
 	pmd_t *pmd;
 	unsigned long k_cur, k_next;
@@ -35,7 +35,10 @@ static int kasan_init_shadow_page_tables(unsigned long k_start, unsigned long k_
 		if ((void *)pmd_page_vaddr(*pmd) != kasan_early_shadow_pte)
-		new = pte_alloc_one_kernel(&init_mm);
+		if (slab_is_available())
+			new = pte_alloc_one_kernel(&init_mm);
+		else
+			new = memblock_alloc(PTE_FRAG_SIZE, PTE_FRAG_SIZE);
 		if (!new)
 			return -ENOMEM;

             reply index

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-31  6:01 Christophe Leroy [this message]
2019-07-31  8:02 ` Christophe Leroy
2019-08-02  2:28 ` Michael Ellerman

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